The Herbalist by Niamh Boyce (Second Hand)

"Out of nowhere the herbalist appears and sets up his stall in the market square. Teenager Emily is spellbound by the exotic stranger - here is a man of the world who won't care that she's not respectable. However, Emily has competition for the herbalist's attentions. It seems the women of her small town are all mesmerized by the visitor who, they say, can perform miracles. When Emily discovers the miracle-worker's dark side, her world turns upside down. She may be naive, but she has a fierce sense of right and wrong. With his fate lying in her hands, Emily must make the biggest decision of her young life. To make the herbalist pay for his sins against the women of the town? Or let him escape to cast his spell on another place?"--Publisher's description.